Hello. I Just received a new GPU, A GTX 680. I have a problem with it. The computer turns on, but the boot menu is very messed up. The entire computer freezes on the boot menu. Keep in mind, I switched from an AMD Radeon 7770. I didn't uninstall the amd drivers. But, could it be my 500W 13A PSU? I have an i7-3770 as well. Everything works fine after reverting back to my AMD 7770. Also, could it also be possible that my GPU is DOA. As it is managing to display something before the computer freezes.